Boulder IO is a simple TAG=VALUE data format designed for sharing data between programs connected via a pipe. It is also simple enough to use as a common data exchange format between databases, Web pages, and other data representations.

The basic data format is very simple. It consists of a series of TAG=VALUE pairs separated by newlines. It is record-oriented. The end of a record is indicated by an empty delimiter alone on a line. The delimiter is "=" by default, but can be adjusted by the user.

Tags can be any alphanumeric character (upper or lower case) and may contain embedded spaces. Conventionally we use the characters A-Z0-9_, because they can be used without single quoting as keys in Perl associative arrays, but this is merely stylistic. Values can be any character at all except for the reserved characters {}=% and newline. You can incorporate binary data into the data stream by escaping these characters in the URL manner, using a % sign followed by the (capitalized) hexadecimal code for the character. The module makes this automatic.

The main component of the Boulder modules is Boulder::Stream, which provides a stream-oriented view of the data. You can read and write to Boulder::Streams via tied filehandles, or via method calls. Data records are flattened into a simple format called "boulderio" format.

This is a simple persistent storage class which allows you to store several (thousand) Stone's into a DB_File database. You must have libdb and the Perl DB_File extensions installed in order to take advantage of this class.

These are parsers and accessors for various biological data sources. They act like Boulder::Stream, but return a set of Stone objects that have certain prescribed tags and values. Many of these modules were written by Luca I.G. Toldo <luca.toldo@merck.de>.

The Stone object encapsulates a set of tags and values. Any tag can be single- or multivalued, and tags are allowed to contain subtags to any depth. A simple set of methods named tags(), get(), put(), insert(), replace() and so forth, allows you to examine the tags that are available, get and set their values, and search for particular tags. In addition, an autoload mechanism allows you to use method calls to access tags, for example:

my @friends = $record->Friends;

is equivalent to:

my @friends = $record->get('Friends');

A Stone::Cursor class allows you to traverse Stones systematically.

A full explanation of the Stone class can be found in its manual page.